Abstract
The Hong Kong Observatory (HKO) has been developing a suite of nowcasting systems to support operations of the forecasting center and to provide a variety of nowcasting services for the general public and specialized users. The core system is named the Short-range Warnings of Intense Rainstorm of Localized Systems (SWIRLS), which is a radar-based nowcasting system mainly for the automatic tracking of the movement of radar echoes and the short-range Quantitative Precipitation Forecast (QPF). The differential, integral (or variational), and object-oriented tracking algorithms were developed and integrated into the nowcasting suite. In order to predict severe weather associated with intense thunderstorms, such as high gust, hail, and lightning, SWIRLS was enhanced to SWIRLS-II by introduction of a number of physical models, especially the icing physics as well as the thermodynamics of the atmosphere. SWIRLS-II was further enhanced with non-hydrostatic, high resolution numerical models for extending the forecast range up to 6 h ahead. Meanwhile, SWIRLS was also modifled for providing nowcasting services for aviation community and specialized users. To take into account the rapid development of lightning events, ensemble nowcasting techniques such as time-lagged and weighted average ensemble approaches were also adopted in the nowcasting system. Apart from operational uses in Hong Kong, SWIRLS/SWIRLS-II was also exported to other places to participate in several international events such as the WMO/WWRP Forecast Demonstration Project (FDP) during the Beijing 2008 Olympics Games and the Shanghai Expo 2010. Meanwhile, SWIRLS has also been transferred to various regional meteorological organizations for establishing their nowcasting infrastructure. This paper summarizes the history and the technologies of SWIRLS/SWIRLS-II and its variants and the associated nowcasting applications and services provided by the HKO since the mid 1990s.
Similar content being viewed by others
References
Albers, S. C., J. A. McGinley, D. L. Birkenheuer, et al., 1996: The Local Analysis and Prediction System (LAPS): Analyses of clouds, precipitation, and temperature. Wea. Forecasting, 11, 273–287.
Aubert, G., R. Deriche, and P. Kornprobst, 1999: Computing optical flow via variational techniques. SIAM J. Appl. Math., 60, 156–182.
Browning, K. A., 1982: Nowcasting. London, Academic Press, 256 pp.
Cao, Y. C., Y. Q. Chen, and P. W. Li, 2006: Wet refractivity tomography with an improved Kalman-filter method. Adv. Atmos. Sci., 23, 693–699.
Chan, P. W., 2009: Nowcasting applications of a microwave radiometer in Hong Kong. Preprint, 8th International Symposium on Tropospheric Profiling: Integration of Needs, Technologies and Applications, Delft, The Netherlands, S11-P02-1. [Available online at http://www.knmi.nl/~apituley/files/istp8/data/1643742.pdf].
Cheng Tsz-lo, Dai Jianhua, and Yeung Hon-yin, 2011: Applications of SWIRLS nowcasting system in the Shanghai Expo 2010. Preprint, 28th Chinese Meteorological Society Annual Meeting, Xiamen, China. (in Chinese)
Cheung, P., and H. Y. Yeung, 2012: Application of optical-flow technique to significant convection now-cast for terminal areas in Hong Kong. The 3rd WMO International Symposium on Nowcasting and Very Short-Range Forecasting, 6–10 August 2012, Rio de Janeiro, Brazil.
Conway, B. J., 1998: An overview of nowcasting techniques. SAF Training Workshop-Nowcasting and Very Short Range Forecasting, 9–11 December 1998, Madrid, Spain, EUMETSAT, 34–33.
Dixon, M., and G. Wiener, 1993: TITAN: Thunderstorm identification, tracking, analysis and nowcasting—A radar-based methodology. J. Atmos. Oceanic Technol., 10, 785–797.
European Space Agency, 1981: Nowcasting: Mesoscale observations and short-range prediction. Proceedings of an International Symposium, 25–28 August 1981, Hamburg, Germany (Part of the IAMAP Third Scientific Assembly), 415 pp.
Hong Kong Observatory, 2012: Thunderstorm Warning. Hong Kong Observatory webpage: http://www.weather.gov.hk/wservice/warning/thunder.htm.
Lai, E. S. T., and P. W. Li, 1999: Preliminary performance evaluation of a rainstorm nowcasting system. Proceedings of the Forth International Conference on East Asia and Western Pacific Meteorology and Climate, Hangzhou, China, 390–400.
Lam, C. Y., 1984: Digital radar data as an aid in now-casting in Hong Kong, nowcasting-II, Mesoscale observations and very-short-range weather forecasting. Proceedings of the Second International Symposium on Nowcasting, Norrköping, Sweden, 249–253.
Li, P. W., W. K. Wong, K. Y. Chan, et al., 2000: SWIRLS—An Evolving Nowcasting System. Technical Note No. 100, Hong Kong Observatory, 33.
—, and E. S. T. Lai, 2004a: Applications of radar-based nowcasting techniques for mesoscale weather forecasting in Hong Kong. Meteor. Applications, 11, 253–264.
—, and E. S. T. Lai, 2004b: Short-range quantitative precipitation forecasting in Hong Kong. J. Hydrology., 288, 189–209.
—, W. K. Wong, and E. S. T. Lai, 2005: RAPIDS—A new rainstorm nowcasting system in Hong Kong. WMO/WWRP International Symposium on Nowcasting and Very-short-range Forecasting, 5–9 September 2005 Toulouse, France. [Available online at http://www.meteo.fr/cic/wsn05/].
—, 2009: Development of a thunderstorm nowcasting system for Hong Kong international airport. First AMS Aviation, Range, Aerospace Meteorology Special Symposium on Weather-Air Traffic Management Integration, Phoenix, Arizona, p16. [Available online at https://ams.confex.com/ams/89annual/techprogram/paper_146911.htm].
—, and W. K. Wong, 2010: Development of an advanced aviation nowcasting system by including rapidly updated NWP model in support of air traffic management, preprints. AMS Aviation, Range, Aerospace Meteorology, Atlanta, Georgia, 5.3. [Available online at https://ams.confex.com/ams/90annual/techprogram/paper_159847.htm].
Liljas, E., 1998: COST-78 co-operations on SAFs. In SAF Training Workshop-Nowcasting and Very Short Range Forecasting, 9-11 December 1998, Madrid, Spain, EUMETSAT, 23–33.
Rinehart, R. E., 1979: Internal storm motions from a single non-Doppler weather radar, NCAR/TN-146+STR, 262 pp.
Robert, A., 1982: A semi-Lagrangian and semi-implicit numerical integration scheme for the primitive meteorological equations. J. Meteor. Soc. Japan, 60, 319–325.
Saito, K., T. Fujita, Y. Yamada, et al., 2006: The operational JMA nonhydrostatic mesoscale model. Mon. Wea. Rev., 134, 1266–1298.
Srivastava, K., S. Y. Lau, L. H. Y. Yeung, et al., 2012: Use of SWIRLS nowcasting system for quantitative precipitation forecast using Indian DWR data. Mausam Quart. J. Meteor., Hydrol. Geophy., 63, 1–16.
Wilson, J. W., Y. Feng, M. Chen, et al., 2010: Nowcasting challenges during the Beijing Olympics: Successes, failures, and implications for future nowcasting systems. Wea. Forecasting, 25, 1691–1714.
Wong, W. K., 2011: Development of operational rapid update non-hydrostatic NWP model and data assimilation system in the Hong Kong Observatory. Technical Reports of the Meteorological Research Institute No. 65: International Research for Prevention and Mitigation of Meteorological Disasters in Southeast Asia, 87–100.
—, L. H. Y. Yeung, Y. C. Wang et al., 2009: Towards the blending of NWP with nowcast-operation experience in B08FDP. 2nd WMO International Symposium on Nowcasting and Very-Short-Range Forecasting, 30 August–4 September 2009, Whistler, Canada.
—, M. K. Or, P. W. Chan et al., 2011: Impact of radar retrieval winds on data assimilation and forecast of a mesoscale convective storm using non-hydrostatic model. 14th AMS Conference on Mesoscale Process, American Meteorological Society, 31 July–4 August 2011, Los Angeles, USA. 8.4. [Available online at https://ams.confex.com/ams/14Meso15ARAM/webprogram/Paper190629. html].
—, C. S. Lau, and P. W. Chan, 2013: Aviation Model: A fine-scale numerical weather prediction system for aviation applications at the Hong Kong international airport. Adv. Meteor., 2013, Article ID 532475, 11.
Woo, W. C., 2013: Location-based rainfall nowcasting service for public. Preprint, European Geosciences Union General Assembly 2013, 7–12 April 2013, Vienna, Austria. EGU2013-2767. [Available online at http://meetingorganizer.copernicus.org/EGU2013/EGU2013-2767.pdf].
World Meteorological Organization (WMO), 2009: WMO Report on Overview of the Beijing 2008 Olympics Project-Part I: Forecast Demonstration Project, 130 pp.
—, 2012: WMO Report on Final Review Meeting for the World EXPO 2010 Nowcasting Services (WENS) Demonstration Project and Capacity-Building Workshop, 14–18 November 2011, Shanghai, China, 26 pp.
Yeung, L. H. Y., E. S. T. Lai, and S. K. S. Chiu, 2007: Lightning initiation and intensity nowcasting based on isothermal radar reflectivity—A conceptual model. The 33rd International Conference on Radar Meteorology, 6–10 August 2007, Cairns, Australia, 11A.7. [Available online at https://ams.confex.com/ams/pdfpapers/123157.pdf].
—, —, and P. K. Y. Chan, 2008: Thunderstorm down-burst and radar-based nowcasting of squalls. Fifth European Conference on Radar in Meteorology and Hydrology, 30 June–4 July 2008, Helsinki, Finland.
—, W. K. Wong, P. K. Y. Chan, et al., 2009: Applications of the Hong Kong Observatory nowcasting system SWIRLS-2 in support of the 2008 Beijing Olympic Games. 2nd WMO International Symposium on Nowcasting and Very-Short-Range Forecasting, 30 August–4 September 2009, Whistler, B. C., Canada.
—, C. Man, S. T. Chan et al., 2012: Application of radar-raingauge co-kriging to improve QPE and quality control of real-time rainfall data. Weather Radar and Hydrology, International Association of Hydrological Sciences Publication No. 351, 231–236.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Li, PW., Wong, WK., Cheung, P. et al. An overview of nowcasting development, applications, and services in the Hong Kong Observatory. J Meteorol Res 28, 859–876 (2014). https://doi.org/10.1007/s13351-014-4048-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s13351-014-4048-9